Porous, Water-Resistant Multifilament Yarn Spun from Gelatin.

Sustainability, renewability, and biodegradability of polymeric material constantly gain in importance. A plausible approach is the recycling of agricultural waste proteins such as keratin, wheat gluten, casein or gelatin. The latter is abundantly available from animal byproducts and may well serve as building block for novel polymeric products. In this work, a procedure for the dry-wet spinning of multifilament gelatin yarns was developed. The process stands out as precipitated gelatin from a ternary mixture (gelatin/solvent/nonsolvent) was spun into porous filaments. About 1000 filaments were twisted into 2-ply yarns with good tenacity (4.7 cN tex(-1)). The gelatin yarns, per se susceptible to water, were cross-linked by different polyfunctional epoxides and examined in terms of free lysyl amino groups and swelling degree in water. Ethylene glycol diglycidyl ether exhibited the highest cross-linking efficiency. Further post-treatments with gaseous formaldehyde and wool grease (lanolin) rendered the gelatin yarns water-resistant, allowing for multiple swelling cycles in water or in detergent solution. However, the swelling caused a decrease in filament porosity from ∼30% to just below 10%. To demonstrate the applicability of gelatin yarn in a consumer good, a gelatin glove with good thermal insulation capacity was fabricated.

Integrity of mechanical aortic valve prostheses explanted after 27 and 23 years.

We describe 2 cases of mechanical aortic valve endocarditis and the influence on clinical outcome and prostheses material integrity. One patient required extensive reconstruction due to active endocarditis leading to a "rocking valve". The second case was caused by late aortic dissection following endocarditis. Both valve prostheses showed remarkable material quality and performance in functional assessment and high resolution scanning electron microscopic evaluation after 27 and 23 years of service.

Rupture of a polypropylene suture after aortic operation: a scanning electronic microscopical assessment of potential mechanisms.

In surgical procedures, and specifically in cardiovascular operations, the polypropylene monofilament is a widely used suture material. We report an unexplained case of early rupture of a 4-0 polypropylene suture used for the distal anastomosis after replacement of the ascending aorta with a Dacron (Vaskutek, Sulzer Medica, Austin, TX) prosthesis. By trying to identify if intraoperative mechanical damage could have led to the rupture, we obtained impressive results of how different manipulations of suture material using surgical instruments can damage those delicate filaments. Pictures were obtained by light microscopy and electron microscopy.